String/Array Question

[Matthew Alton]

Why does this code generate a SIGSEGV?

#include <stdio.h>

int
main(void)
{
char *s = "ABC";

s[1] = 'X';

return(0);
}

while this does not:

#include <stdio.h>

int
main(void)
{
char s[] = "ABC";

s[1] = 'X';

return(0);
}
The *s declaration followed by a reference to s[-1] is used in
FreeBSD's strsep(3). It dumps core on Red Hat Linux 7.x and NetBSD
1.6.1.

[Irrwahn Grausewitz]

ma****@myit.biz (Matthew Alton) wrote:

Why does this code generate a SIGSEGV? char *s = "ABC";
s[1] = 'X';

http://www.eskimo.com/~scs/C-faq/top.html Question 1.32

Regards
--
Irrwahn Grausewitz (ir*******@freenet.de)
welcome to clc: http://www.ungerhu.com/jxh/clc.welcome.txt
clc faq-list : http://www.faqs.org/faqs/C-faq/faq/
clc OT guide : http://benpfaff.org/writings/clc/off-topic.html

[Barry Schwarz]

On 24 Apr 2004 17:03:01 -0700, ma****@myit.biz (Matthew Alton) wrote:

Why does this code generate a SIGSEGV?

#include <stdio.h>

int
main(void)
{
char *s = "ABC";

s[1] = 'X';

return(0);
}

while this does not:

#include <stdio.h>

int
main(void)
{
char s[] = "ABC";

s[1] = 'X';

return(0);
}

Because your compiler is doing it best to comply with the requirement
that a string literal be non-modifiable. See the faq at
http://www.eskimo.com/~scs/C-faq/top.html. The answer to your
question is near the beginning but you should read the whole thing.
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